With sluggish crop: Defoliation timing can be tricky

A cool snap in the weather the second week of August is blamed for the “sluggishness” of the Mid-South's cotton crop. Throughout the region, farmers, consultants and agronomists wait on the proverbial “pot to boil.”

However, as the temperatures heat up and scattered rains fall daily, cotton is growing again. Compared to recent years, however, the cotton is five to 15 days behind schedule.

Bill Kennedy, manager of Duncan Gin in Inverness, Miss., where early cotton isn't unusual, said on Aug. 24 he wasn't expecting cotton delivery for another two to three weeks. He says during the cool weather cotton in his area “just sat there.”

“We didn't get any growth, and now this cotton has some growing to do,” he said.

The lateness of the crop changes late-season management as growers evaluate planned defoliation programs to be sure they are still the best.

“Poor timing of defoliation or not choosing the best material or tank mix for defoliation can hurt yields and more likely than not will hurt quality,” says Charles Ed Snipes, the Delta cotton agronomist with the MSU Extension Service.

“Farmers and ginners of this region are learning to consider quality when they make variety and production decisions. We've farmed so many years with our eyes focused on quantity, but now the reputation of this region's cotton and the future marketability of our cotton are at risk because of the quality of our cotton. Whether it be too much trash, off color or high or low micronaire, we are getting a reputation for poor quality cotton,” says Snipes. “I believe, however, we can turn things around.

“Even though it appears we are going to be picking a late crop, it is certainly not the latest crop we've harvested. If we pay attention to what needs to be done when, and take care of this crop from here on out, we still have the potential for good yields and good quality.

“In our plots here on the station, cotton just isn't where we thought it would be by now (Aug. 25). Normally we would be much closer to defoliation. Growers can't manage this crop based on any previous calendar. They should make decisions on a field-by-field basis and be ready when the cotton is ready.”

Steve Martin, an agricultural economist at the Delta Research and Extension Center, says the 2002 harvest season is still vivid in the minds Delta cotton farmers.

Several hurricanes over the Gulf of Mexico brought heavy rains, and much of the Mississippi's cotton crop was stranded in the fields. Yields and quality were reduced by the prolonged and unusually wet late summer and fall.

“Two years ago, when the harvest was pushed so late,” says Martin, “growers received quality discounts of 3 cents early in ginning just from trash content and high micronaire, but as they continued ginning, the discounts tended to go up until they were getting discounts of 15 and 20 cents per pound.

“With prices at 52 cents, the basis would put the price down to around 45 cents in the Delta, minus any other quality discounts,” says Martin. “Quality discounts are a higher percentage of your total income when you have low cotton prices. Farmers pay more attention to quality when the prices are low — when even small discounts really hurt.

“If a grower loses 3 cents to quality discounts on 30-cent cotton, that's 10 percent of his income. When cotton is 70 cents, it's less than 2 to 3 percent of his income.”

Most people will go into a loan or into the LDP with the 52 cents, but they still can get quality discounts off that, says Martin.

The economist says growers can't assume they can put their cotton into the loan, and they can't assume they will get the loan rate.

“We have two things to consider. First, the cotton must be good enough to get into the loan, and, most of it will be. Second, even if it does go into the loan, it is still discounted if the quality is not there. Growers will not automatically get 52 cents. That's the starting point, and it is adjusts down accordingly,” says Martin.

MSU Extension cotton specialist Tom Barber agrees with the cotton assessments taking place throughout the Delta. “Defoliation decisions in Mississippi and throughout the central Delta will be challenging this year because of the differences in maturity of the crop coupled with cooler temperatures in August,” says Barber “We were headed for a Sept. 1 defoliation on the early-planted cotton, however, the cooler temperatures slowed our plans.

“The later-planted crop will be further delayed by the cooler temperatures, and it will be more difficult to determine defoliation timing. Boll retention and maturity of this later crop varies.”

Many cotton fields have gaps in the middle in regards to boll set. With open bolls on the bottom, then a big gap before the upper crop is set, sacrifices of the bottom bolls may be made to wait on the top crop.

“The problem is the cooler temperatures in August delayed our top crop and left us with difficult decisions to make,” says Barber

Barber and Snipes agree that trying to determine when to defoliate this variable crop is going to be tough.

“It is important to hold off defoliating until the majority of the crop in the field is 50 to 60 percent open,” says Barber. “Unfortunately, even with the earlier crop, this will not occur as quickly as growers might think because of the cooler temperatures in August. A typical August day will produce from 20 to 25 DD-60s. says Barber. “With the cooler weather during the first and second week of August, we only accumulated 6 to 12 DD-60s a day.”

The typical boll requires an average of 40 days for development in normal conditions (20 to 25 heat units per day). However, because of the cooler temperatures, the uppermost boll that growers want to harvest will require more time to develop.

“Keeping this in mind, most important is to not defoliate too quickly. Growers should make sure the majority of their fields are 50 to 60 percent open (taking in account the gaps).

“And a close inspection of the maturity of the uppermost bolls they want to harvest is critical,” warns Barber. The inspection can be done with a sharp knife, cutting the uppermost boll that is wanted for harvest. The boll should have a mottled color and be hard to cut. Once it is cut, look closely at the seed. If the seed has no soft jelly in the center and a dark ring is apparent around the seed coat, the boll is mature and ready for defoliation.

The lateness of this crop could tempt some growers to defoliate too early, but according to Barber, if cotton is defoliated too quickly the fiber quality and yield of the top crop will be affected. On the other hand, waiting too late could affect the quality of the lower bolls.

Cooler weather can affect the activity of harvest aid and defoliation products in respect to time. If nights continue around 55 degrees, activity of the products in general will be slower in both defoliation and boll opening.

“With this in mind, increased rates of the products may be necessary to get the results wanted,” says Barber.

Sandy Stewart, Extension cotton specialist, LSU Ag Center, says there is always a balancing act between yield and quality when defoliating cotton, but close attention to individual fields can help quality while preserving yield. No one way is best for timing defoliation. Each method has strengths and weaknesses.

Stewart recently published three information sheets that outline factors growers should consider for the remainder of this year's crop, including when to terminate insecticides, defoliation timing methods, and complete list of defoliation materials available for 2004. For a copy of the information, contact Stewart at 318-473-6522 or sstewart@agcenter.lsu.edu.

Among Stewart's published recommendations is advice for managing newer, full-season varieties.

“Our limited experience with these full-season varieties suggests they may cut out slower than the early-season varieties. The implication for defoliation timing is these varieties are more likely to continue to produce small, green bolls in the tops of plants. The value of waiting on these bolls is questionable, especially considering the relative lack of stormproofness of the varieties,” says Stewart.

“The temptation, however, will be great to wait on those bolls at the top of the plant. It is advisable to go after the crop that is already made. In many cases, these varieties may need to be picked with some green bolls at the top of the plant, but this can be done without reducing overall yield.”

Eva Ann Dorris is an ag journalist from Pontotoc, Miss. She can be reached at 662-419-9176 oreadorris@aol.com.